Feed apparatus for platen presses



Dec. 6, 1960 A. BUTTNER FEED APPARATUS FOR PLATEN PRESSES 2 Sheets-Sheet 1 Filed Aug. 5, 1958 Dec. 6, 1960 A. BUTTNER 2,963,292

FEED APPARATUS FOR PLATEN PRESSES Filed Aug. 5, 1958 2 Sheets-Sheet 2 FIG. 5.

FEED APPARATUS non PLATEN runssns Artur Biittner, Heidelberg, Germany, assignor to Schnellpressenfabrik Aktieug'esellschaft Heidelberg, Heidelberg, Germany, a corporation of Germany This invention relates generally to platen printing presses and more particularly to platen printing press feed apparatus.

In known platen printing presses the feed systems or apparatus are usually provided with a sucker bar that picks up the individual sheets momentarily from a stack of sheets and transfers them to a gripper system which is operated to position the sheets successively on a platen cooperating with a form to make an impression. In such feed systems the usual practice is to construct them such that the application of a vacuum suction to the sucker bar is discontinued substantially immediately upon transfer of a sheet to the grippers consequently allowing the individual sheet to be drawn longitudinally by the grip persover the end of the platen'without any assistance by the sucker bar.

When handling heavy or standard stock such feed systems or apparatus encounter no difficulty, however, it has been found that when transferring light stock such as airmail paper and onion skin paper it is not possible for the individual sheets to be delivered by the grippers on to the platen without creasing and crumpling the sheets as they are dragged over the end of the platen. Accord ingly it is the usual practice in operating platen presses to reduce the operational speed of the printing press when light or thin stock is being handled or printed thereon. For example, when handling standard and heavy stock the printing press may operate at a speed of 5,000 impressions per hour .but this speed must be reduced considerably when the machine is handling light stock.

It is a principal object of the invention to provide a sheet feed apparatus making it possible to deliver individualsheets to a printing press gripper system which then transfers the individual sheets to the platen without wrinkling ,or creasing them in any manner whatsoever.

Another object of the present invention is to provide a feed apparatus for platen printing presses whereby heavy, standard, and light or thin stock can all be hand es at t e same r t o l Sp SO that t p n press can operate at a maximum and optimum operational speed ,for effecting the maximum number of impressions per hour regardless of the stock being handled thereby to increase the production output of the printing press when printing on light and thin stock.

A feature of the sheet feeding apparatus in accordance with the present invention is that it is provided with a vacuum suction control unit for controlling the application of a vacuum suction to a sucker bar. The control unit operatively connects the sucker bar to a source of vacuum so that the sucker bar can lift the top sheet of a stack .of printing stock by the application of a vacuum suction thereto, and to the individual suckers on the bar and, then transfer the sheet to grippers which grip the leading edge of the sheet and which are then operated to position the sheets successively on the platen prior to each successive printing operation. The control unit interrupts the application ofa vacuum suction to the sucker bar substantially immediately after the individual sheets are transferred or thrown ofi to the grippers. The vacuum suction is then re-established so that the sucker bar can effectively carry out the next successive sheet-lifting operation.

In accordance with the invention the means providing the interruption of the vacuum suction pressure can be rendered ineffective at will so that a vacuum suction is applied to the sucker bar continuously throughout its entire cycle of operation.

In this manner when the suction bar lifts a sheet clear of the stack and delivers it to the grippers, the suction is continuously applied to the sheet so that the grippers grip the leading edge of the sheet and as they move it in a longitudinal direction to position it on the platen the sheet is maintained taut and under a slight tension so that the sheet slides across the tips of the individual suckers and is held in a raised position by them so that there is no tendency to wrinkle or crease the sheets by dragging them longitudinally over the end of the platen in the manner of known feed apparatus for platen presses.

Other features and advantages of the apparatus in accordance with the present invention will be better understood as described in the following specification and appended claims, in conjunction with the following drawings in which i Fig. l is a fragmentary diagrammatic side elevation view' of the feed end of a platen press having a vacuum suction control unit according to the invention;

Fig. 2 is a fragmentary front elevation view ofrthe printing front elevation view of the printing press shown in Fig. 1 and shows the suction bar in detail with a vacuum control suction unit according to the invention;

Fig. 3 is a sectional view, on an enlarged scale, of the vacuum suction control unit shown in Figs. 1 and 2;

Fig. 4 is a fragmentary diagrammatic side elevation view of the platen press shown in Fig. 1 illustrating the sheet transfer and feed operation according to the present invention;

5 is a plan view of the platen press in Fig. l illustrating the sheet delivery and positioning operation as seen in plan.

While the present invention is primarily applicable to and will be described in conjunction with aplaten printing press it will be understood that the principles of the present invention are applicable to other sheet handling apparatus wherein the sheet feed is accomplished with a vacuum suction device cooperating with grippers.

As shown in the drawings the printing press comprises a frame 1 in which is mounted a platen 2 shown in a sheet-receiving position and is operable, in known manner by means not shown, between this position and an operative position cooperating with form 9 for effecting an impression on a sheet carried by the platen. The frame 1 is provided with an arm 3 on which is mounted a sheet support means or feed table 4 for holding a stack of sheets thereon. The printing press is provided with known means not shown, for constantly and automatically raising the feed table step-by-step for maintaining the top sheet of the stack in a predetermined position.

A sucker bar 6 having a plurality of individual suckers 7, as shown, is mechanically connected to a vacuum suction control unit 11 mounted at one end of rocker arm lever 10 (Figs. 1 and 2). The lever 10 is rocked .or oscillated, in known manner by means not shown, sothat the sucker ,bar 6 is cyclically operated or raised and lowered between a lowermost or lower terminal position 6 and an uppermost or terminal position a" and passesthrough an intermediate position. The vacuum suction control unit 11 is connected through a flexible conduit 12 to a source of vacuum, as for example, a pump not shown,

and controls the application of a vacuum suction to suc tion bar 6 through a flexible conduit 13 in a manner herein later described.

The printing press is provided with a rotary gripper system mounted on the platen (Fig. 5) with the indiva sheet transfer the grippers are then operated to position the sheets one-by-one on the platen prior to each successive printing operation. In the known platen press feed apparatus, and in the present invention, the sucker bar is moved to its lower terminal position wherein it engages the top sheet of the stack 5 (Fig. 4) and subsequently delivers it to grippers 8 at the: intermediate posi tion which draw the sheet over a sheet guide plate such as 22 (Fig. 5) and position it on the platen 2 while it is moving toward the printing position engaging the form 9. However, in known feed apparatus the vacuum suction to the sucker bar 6 is interrupted substantially immediately after the individual sheets are thrown off or transferred to the grippers 8 so that the sheet may be moved longitudinally without being subjected to the application of a vacuum suction while being positioned on the platen 2. It has been found that with heavy and regular stock no trouble is encountered, however,

.when thin stocks are being handled by the sheet feed apparatus the sheets will droop in the manner as shown at 21 so that as the sheet is moved longitudinally over the sheet guide 22 there is a tendency to wrinkle and crease the light stock sheets. Heretofore it has been necessary to decrease the operational speed of the entire printing press cycle so that the gripper speed could be decreased thereby allowing the sheets to be moved over the guide 22 at a lower speed in order to preclude damaging and wrinkling them.

With the present invention, however, when thin stocks are being handled by the feed apparatus the vacuum suction to the sucker bar 6 is not interrupted subsequent to the transfer or the throw-01f operation so that the individual sheets are constantly held by suction against the tips fthe suckers 7 after the grippers 8 gri the leading edge and a slight tension is thereby applied to the individual sheets as they are moved longitudinally while in contact with the suckers 7 with the suckerbar in the intermediate position and as it is raised to terminal position 6". Thus an individual sheet does not droop downwardly and is transferred onto the platen as shown at 21 in Fig. 4 thereby the drooping of li ht stocks is precluded as well as the damage and wrinkling thereof. It can readily be seen that with the sucker bar effecting the throw-off operation while in an intermediate position and while moving toward the raised or uppermost terminal position an individual sheet is delivered substantially in the plane of the platen 2 as it moves in the direction of form 9 thereby precluding wrinkling and damaging of the sheet.

The vacuum suction control unit 11 according to the invention comprises a housing 11 having a passageway 14 in communication with a chamber 24 with which conduits 12 and 13 also communicate. A pivotally mounted lever 16 depending downwardly from housing 11 carries a flapper or clack valve 15 and supports a rotatable cam follower 17. A spring loaded finger 25 constantly biases the valve 15 in a direction toward a closed position so that the cam follower 17 is in constant engagement with a cam surface 18 adjustably mounted on the frame of the machine.

The cam 18 is so constructed that flapper valve 15 closes the passageway 14 as the vacuum controlled suction unit 11 and the sucker bar 6 are moved downwardly in a direction toward terminal position 6' so that chamber 24 is under a vacuum and therefore the sucker bar has a suction applied thereto. As the suckers 7 engage the top sheet of stack and the arm moves the sucker bar to the intermediate position, the flapper valve 15 continues to close passageway 14. After the individual is transferred to the rotary gripper system, the sucker bar continues its upward travel so that cam follower 17 engages a high portion of cam 18 moving the lever 16 in a direction toward the right thereby unseating valve 15 and placing passageway 14 in communication with the atmosphere so that the vacuum is broken in chamber 24 and in the sucker bar. On the subsequent downward movement the valve 15 again closes passageway 14 and the cycle is repeated.

It will be understood that a slide valve or spool valve 23, having a transverse passageway must be in the position shown in Fig. 3 to properly align its transverse passageway as shown with passageway 14 for the unit to function as discussed heretofore. When the slider 23 is at its position a ball forming the opposite end of the finger 25 engages a notch in the slider 23 and locks it into position as shown. Moreover, it will be understood that when the slider 23 is in the position shown in Fig. 3, the control unit is set for handling regular and heavy stock.

When it is desired to shift to thin stocks, according to the invention, the slider 23 is manually tripped or operated to a position blocking or closing off passageway 14 by moving the slider or trip 23 in a direction toward the left from the position shown in Fig. 3. In this manner the cam operated valve 15 is rendered ineffective and chamber 24 is under vacuum suction throughout the cycle so that the suction bar 6 has a vacuum suction applied thereto continuously throughout its entire operating cycle. Thus when the top sheets of stack 5 are successively lifted by the suckers 7 and the sucker bar is moved to its intermediate position for transferring the individual sheets to the grippers 8, the suction bar remains under suction so that as the sucker bar moves the sheet longitudinally in a direction to position it on platen 2 the sheet is held in a raised position and continues in contact with the sucker bar tips 7 during the upward travel of the sucker bar so that the sheet is never allowed to droop downwardly and is transferred substantially in the plane of platen 2. In this manner the cycle of the rotary system need not be decreased and the overall cycle of the machine is the same when printing is being effected on heavy, standard and thin stocks.

In order to render the suction bar completely inelfective the vacuum suction control unit 11 is provided with a manual trip comprising a slider or spool valve 20 movable longitudinally in the manner similar to manual trip 23 to a position as shown in dotted lines in Fig. 3 so that a passageway 19 communicating with the atmosphere is placed in communication with the chamber 24 thereby precluding the application of a vacuum suction to suction bar 6. When the trip 20, is in a position shown by the solid lines in Fig. 3, the passageway 19 is effectively closed off and the control unit functions as heretofore indicated. A spring loaded catch 26 is provided for retaining the trip 20 in either of the two positions.

While a preferred embodiment of the invention has been shown and described it will be understood that many modifications and changes can be made within the scope of the invention.

What I claim and desire to secure by Letters Patent is:

1. In a platen printing press having, a platen cyclically operable between a sheet-receiving position and an operative position for printing, a gripper system having grippers cyclically operable to receive and releasably grasp individual sheets and means to cause the grippers to advance the sheets after grasping them and position them one-by-one on said platen prior to each successive printing operation, means for holding and supporting a stack of sheets thereon in position for the top sheet of the stack to be constantly maintained in a predetermined position, a sucker bar cyclically operable for lifting the top sheets of the stack one-by-one from substantially adjacent a leading edge thereof and delivering them successively to said grippers for advancement relative to .the sucker bar for transfer to the platen, means comprising a vacuum suction control unit to control the application of a vacuum suction to the sucker bar during the lifting of the individual sheets and while the individual sheets are being transferred to the platen, the control unit having means to cyclically interrupt the application of the vacuum suction to the sucker bar substantially immediately after each transfer of a sheet to. the grippers and to subsequently reestablish the suction prior to the next successive sheet-lifting operation, and means in said control unit operable at will to selectively render ineffective the interrupting means and effectively continuously apply a vacuum suction to the sucker bar during the lifting of the sheets, the successive sheet-transfer operations to the grippers, and during the advancement of the individual sheets thereby to hold the sheets in contact with the suction bar and to apply a slight tension to the sheets without tearing them during relative travel between the sheets and he suction bar upon advancement and transfer thereof to the platen by the grippers.

2. In a platen printing press having, a platen cyclically operable between a sheet-receiving position and an operative position for printing, a gripper system having grippers cyclically operable to receive and releasably grasp individual sheets at a predetermined position and then operable to advance the sheets to position them one-byone on said platen prior to each successive printing operation, a feed table for holding a stack of sheets thereon in position for the top sheet of the stack to be constantly maintained in a predetermined position, a sucker bar cyclically operably for lifting the top sheets of the stack one-by-one from substantially adjacent a leading edge thereof and delivering them successively to said grippers for advancement relative to the sucker bar for transfer to the platen, means comprising a vacuum suction control unit to control the application of a vacuum suction to the sucker bar for lifting of the individual sheets and while the individual sheets are being transferred to the platen, the control unit having mean-s to cyclically interrupt the application of the vacuum suction to the sucker bar substantially immediately after each transfer of a sheet to the grippers and to subsequently re-establish the suction prior to the next successive sheet-lifting operation, means in said control unit operable at will to selectively render ineffective the interrupting means and effectively continuously apply a vacuum suction to the sucker bar during the lifting of the sheets, the successive sheettransfer operations to the grippers, and during the advancement of the individual sheets thereby to hold the sheets in contact with the suction bar and to apply a slight tension to the sheets without tearing them during relative travel between the sheets and the suction bar upon advancement and transfer thereof to the platen by the grippers, and means operable at will to selectively connect the control unit to the atmosphere thereby to preclude the application of a vacuum suction to the sucker bar.

3. In a platen printing press having, a platen cyclically operable between a sheet-receiving position and an operative position for printing, a grip-per system having gripers cyclically operable to receive and releasably grasp individual sheets at a predetermined position and means to cause the grippers to advance the sheets after grasping them and then position the sheets one-by-one on said platen prior to each successive printing operation, a feed table for holding a stack of sheets thereon, means to automatically maintain the feed table in position for the top sheet of the stack thereon to be constantly maintained in a predetermined position, a sucker bar cyclically operable for lifting the top sheets of the stack one-by-one from substantially adjacent a leading edge thereof and delivering them successively to said, grippers for advancement relative to the sucker bar for transfer to the platen, means comprising a vacuum suction control unit to control the application of a vacuum suction to the sucker bar during the lifting of the individual sheets and While the individual sheets are being transferred to the platen, the control unit having means to cyclically connect the control unit to atmosphere thereby to interrupt the application of the vacuum suction to the sucker bar substantially immediately after each transfer of a sheet to the grippers and to subsequently reestablish the vacuum suction prior to the next successive sheet-lifting operation, and means in said control unit operable at will to selectively render ineffective the interrupting means and effectively continuously apply a vacuum suction to the sucker bar during the lifting of the sheets, the successive transfer operations to the grippers, and during the advancement of the individual sheets thereby to hold the sheets in contact with the suction bar and to apply a slight tension to the sheets Without tearing them during relative travel between the sheets and the suction bar upon advancement and transfer thereof to the platen by the gripper.

4. In a platen printing press having, a platen cyclically operable between a sheet-receiving position and an operative position for printing, a gripper system having grippers cyclically operable to receive and releasably grasp individual sheets at a predetermined position and means to cause the grippers to advance the sheets after grasping them and then position the sheets one-by-one on said platen prior to each successive printing operation, a feed table for holding a stack of sheets thereon, means to automatically maintain the feed table in position for the top sheet of the stack thereon to be constantly maintained in a predetermined position, a sucker bar cyclically operable for lifting the top sheets of the stack one-byone from substantially adjacent a leading edge thereof and delivering them successively to said grippers for advancement relative to the sucker bar for transfer to the platen, means comprising a vacuum suction control unit to control the application of a vacuum suction to the sucker bar during the lifting of the individual sheets and While the individual sheets are being transferred to the platen, the control unit having cam-operated valve means to cyclically interrupt the application of the vacuum suction to the sucker bar substantially immediately after each transfer of a sheet to the grippers and to subsequently re-establish the suction prior to the next successive sheet-lifting operation, and means in said control unit operable at will to selectively render inneffective the interrupting means and effectively continuously apply a vacuum suction to the sucker bar during the lifting of the sheets, the successive transfer operations to the grip pers, and during the advancement of the individual sheets thereby to hold the sheets in contact with the suction bar and to apply a slight tension to the sheets without tearing them during relative travel between the sheets and the suction bar upon advancement and transfer thereof to the platen by the grippers.

5. In a sheet handling machine having, sheet-receiving means cyclically operable between a sheet-receiving position and a second operative position for printing, a gripper system having grippers cyclically operable to receive and grasp individual sheets at a predetermined position, means to cause the grippers to advance the sheets after grasping them and then position the sheets oneby-one on said sheet-receiving means and prior to eaci successive printing operation, a feed table for holding a stack of sheets thereon in position for the top sheet of the stack thereon to be constantly maintained in a predetermined position, a sucker bar cyclically operable for lifting the top sheets of the stack one-by-one from substantially adjacent a leading edge thereof and delivering them successively to said grippers for advancement relative to the sucker bar for transfer to the sheet-receiving means, means comprising a suction control unit to control the application of a suction to the sucker bar during the lifting of the individual sheets and while the individual sheets are being transferred to the sheet-receiving means, the control unit having means to cyclically interrupt the application of suction to the sucker bar substantially immediately after each transfer of a sheet to the grippers, and means in said control unit operable at will to selectively render ineffective the interrupting means thereby to continuously apply a suction to the sucker bar during the lifting of the sheets, the successive sheet-transfer operations to the grippers, and during the advancement of the individual sheets thereby to hold the sheets in contact with the suction bar and to appiy a slight tension to the sheets without tearing them during relative travel between the sheets and the suction bar upon advancement and transfer thereof to the platen by 5 the grippers.

References Cited in the file of this patent UNITED STATES PATENTS 

